The meniscus is a crescent-shaped disc of cartilage tissue located between the femoral condyles and the tibial plateau. The meniscus functions as a shock absorber, absorbing the compressive and shear forces in the knee joint. Since the meniscus is aneural, the load-bearing function occurs in a painless fashion in a healthy knee joint. The meniscus also provides a low-friction surface for articulation within the knee joint.
The meniscus is frequently damaged in twisting injuries or with repetitive impact over time. Meniscus degeneration also can occur by aging: as a person ages, the meniscus becomes soft in the middle and even common motions such as squatting can cause meniscal tears.
Surgical procedures for treating meniscal damage can be broadly classified as either tear repairs or menisectomies. A tear repair is most commonly performed when the tear is a clean longitudinal vertical lesion in the vascular red-red zone of the meniscus. The basic strategy is to stabilize the tear by limiting or eliminating radial separation of the faces of the tear when the meniscus is load bearing. Devices for use in meniscal tear repair are available on the market, including, for example, the RAPIDLOC Meniscal Repair System available from DePuy Mitek of Westwood, Mass. and Somerville, N.J.
Menisectomies involve the surgical removal of part of the meniscus. Such procedures have generally been performed in cases of radial tears, horizontal tears, vertical longitudinal tears outside the vascular zone, complex tears, or defibrillation. Although menisectomies provide immediate relief to the patient, in the long term the absence of part of the meniscus can cause cartilage wear on the condylar surface, eventually leading to arthritic conditions in the joint.
A variety of orthopaedic implants are available for treating damaged soft tissue. Orthopaedic implants for treatment of damaged menisci are disclosed in the following U.S. Pat. Nos. 6,042,610; 5,735,903; 5,681,353; 5,306,311; 5,108,438; 5,007,934; and 4,880,429.
Tear repairs and menisectomies are commonly performed arthroscopically. In arthroscopy, small incisions are made at the affected joint to form portals for the insertion of instruments, including a small lens and lighting system (an arthroscope). The arthroscope is connected to a viewing device, such as a television camera to allow the surgeon to see the interior of the joint. Other instruments are inserted through other portals to perform a variety of tasks. For example, the surgical instrument may include an implement for manipulating the native meniscal tissue (for example, tissue grasping, tissue cutting, bone abrading), or an implement for introducing and implanting a therapeutic implant.
While arthroscopic instruments, such as cannulae and obturators or trocars have been available for use in tear repairs and menisectomies, there remains a need for a device that can be used to deliver a therapeutic implant to the tissue defect site and to manage the sutures used in fixating the therapeutic device to the native meniscus.